names = ['Alex',"Tenglan",'Eric']

 >>> names[0]

 'Alex'

 >>> names[2]

 'Eric'

 >>> names[-1]

 'Eric'

 >>> names[-2] #还可以倒着取

 'Tenglan'

 names = ("alex","jack","eric")

 for i,v in enumerate(range(3,10)):

     print(i,v)

0 3

1 4

2 5

3 6

4 7

5 8

6 9

Process finished with exit code 0

 #!/usr/bin/python

 # -*- coding: UTF-8 -*-

 #blog:http://www.cnblogs.com/linux-chenyang/

 #

 #----------------readme-------------------------

 #1.启动程序后输入你的工资，然后打印商品列表。

 #2.如果选择的是列表内的商品，则进行下一步，否则提示没有这个商品。

 #3.如果选择的商品小于工资，则显示余额，大于工资则显示还差多少钱。

 #4.选择exit退出并且显示消费的钱和余额。

 product_list = [

     ["Iphone7",6500],

     ["MackBook",12000],

     ["Python book",60],

     ["Bike",300],

     ["coffee",30],

 ]

 shoppint_cart = []

 salary = int(input("Please youer salary:"))

 while True:

     for index,i in enumerate(product_list):

         print("%s.\t%s\t%s" %(index,i[0],i[1]))　　　　　　　　　　　　　　　　　　　　　　#\t表示空格。

     choice = input(">>:").strip()　　　　　　　　　　　　　　　　　　　　　　　　　　　　　  #strip（）表示去除空格。

     if choice.isdigit():　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　   #isdigit（）检测字符串是否只由数字组成。

         choice = int(choice)

         if choice < len(product_list) and choice >=0:

             product_item = product_list[choice]　　　　　　　　　　　　　　　　　　　　　　#选择的商品

             if salary >= product_item[1]:

                 salary -= product_item[1]　　　　　　　　　　　　　　　　　　　　　　　　　 #剩余的钱

                 shoppint_cart.append(product_item)　　　　　　　　　　　　　　　　　　　   #添加至购物车

                 print("%s已经加入到你的购物车，余额还剩%s" %(product_item[0],salary))

             else:

                 print("对不起你的余额不足，还差",product_item[1]-salary)　　　　　　　　　　#商品价格减去剩余的钱就少还差多少钱

         else:

             print("没有这个商品！")

     elif choice == "exit":

         total_cost = 0

         print("你已经添加到购物车的东西是：")

         for i in shoppint_cart:

             print(i)

             total_cost += i[1]　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　#循环加购物车里的钱

         print("您总共消费为",total_cost )

         print("您的余额是", salary)

         break

     else:

         print("非法的输入，请选择商品序号或者退出exit")

Please youer salary:5000

0.    Iphone7    6500

1.    MackBook    12000

2.    Python book    60

3.    Bike    300

4.    coffee    30

>>:2

Python book已经加入到你的购物车，余额还剩4940

0.    Iphone7    6500

1.    MackBook    12000

2.    Python book    60

3.    Bike    300

4.    coffee    30

>>:3

Bike已经加入到你的购物车，余额还剩4640

0.    Iphone7    6500

1.    MackBook    12000

2.    Python book    60

3.    Bike    300

4.    coffee    30

>>:4

coffee已经加入到你的购物车，余额还剩4610

0.    Iphone7    6500

1.    MackBook    12000

2.    Python book    60

3.    Bike    300

4.    coffee    30

>>:3

Bike已经加入到你的购物车，余额还剩4310

0.    Iphone7    6500

1.    MackBook    12000

2.    Python book    60

3.    Bike    300

4.    coffee    30

>>:exit

你已经添加到购物车的东西是：

['Python book', 60]

['Bike', 300]

['coffee', 30]

['Bike', 300]

您总共消费为 690

您的余额是 4310

Process finished with exit code 0

#方法1

for key in info:

    print(key,info[key])

#方法2

for k,v in info.items(): #会先把dict转成list,数据里大时莫用

    print(k,v)

 names = {

     "":{"name":"chenlijun","age":22,"hobbie":"girl",},

     "":"lijun",

     "":"xiaoyu",

 }

 #search

 print(names)

 print(names[""])

 print(names[""]["hobbie"])

 print(names.get("",""))

 #add

 names[""] = ["zhouxingchi","","DBA"]

 print(names)

 #update

 names[""][0] = "xingye"

 print(names)

 #del

 print(names.pop(""))

 print(names)

 print(names.pop("","没有这个号码"))

 del names[""]

 print(names)

{'': {'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}, '': 'xiaoyu', '': 'lijun'}

{'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}

girl

87654321

{'': {'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}, '': 'xiaoyu', '': 'lijun', '': ['zhouxingchi', '', 'DBA']}

{'': {'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}, '': 'xiaoyu', '': 'lijun', '': ['xingye', '', 'DBA']}

['xingye', '', 'DBA']

{'': {'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}, '': 'xiaoyu', '': 'lijun'}

没有这个号码

{'': {'age': 22, 'hobbie': 'girl', 'name': 'chenlijun'}, '': 'xiaoyu'}

Process finished with exit code 0

name.capitalize()  首字母大写

name.casefold()   大写全部变小写

name.center(50,"-")  输出 '---------------------Alex Li----------------------'

name.count('lex') 统计 lex出现次数

name.encode()  将字符串编码成bytes格式

name.endswith("Li")  判断字符串是否以 Li结尾

 "Alex\tLi".expandtabs(10) 输出'Alex      Li'， 将\t转换成多长的空格

 name.find('A')  查找A,找到返回其索引， 找不到返回-1 

format :

    >>> msg = "my name is {}, and age is {}"

    >>> msg.format("alex",22)

    'my name is alex, and age is 22'

    >>> msg = "my name is {1}, and age is {0}"

    >>> msg.format("alex",22)

    'my name is 22, and age is alex'

    >>> msg = "my name is {name}, and age is {age}"

    >>> msg.format(age=22,name="ale")

    'my name is ale, and age is 22'

format_map

    >>> msg.format_map({'name':'alex','age':22})

    'my name is alex, and age is 22'

msg.index('a')  返回a所在字符串的索引

'9aA'.isalnum()   True

''.isdigit() 是否整数

name.isnumeric

name.isprintable

name.isspace

name.istitle

name.isupper

 "|".join(['alex','jack','rain'])

'alex|jack|rain'

maketrans

    >>> intab = "aeiou"  #This is the string having actual characters.

    >>> outtab = "" #This is the string having corresponding mapping character

    >>> trantab = str.maketrans(intab, outtab)

    >>>

    >>> str = "this is string example....wow!!!"

    >>> str.translate(trantab)

    'th3s 3s str3ng 2x1mpl2....w4w!!!'

 msg.partition('is')   输出 ('my name ', 'is', ' {name}, and age is {age}') 

 >>> "alex li, chinese name is lijie".replace("li","LI",1)

     'alex LI, chinese name is lijie'

 msg.swapcase 大小写互换

 >>> msg.zfill(40)

'00000my name is {name}, and age is {age}'

>>> n4.ljust(40,"-")

'Hello 2orld-----------------------------'

>>> n4.rjust(40,"-")

'-----------------------------Hello 2orld'

>>> b="ddefdsdff_哈哈"

>>> b.isidentifier() #检测一段字符串可否被当作标志符，即是否符合变量命名规则

True

 names = {

     "":{"name":"chenlijun","age":22},

     "":"lijun",

     "":"xiaoyu",

 }

 n2 = names.copy()

 print(names)

 print(n2)

 names[""] = "LIJUN"

 print(names)

 print(n2)

 names[""]["age"] = 24

 print(names)

 print(n2)

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 22}, '': 'lijun'}

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 22}, '': 'lijun'}

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 22}, '': 'LIJUN'}

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 22}, '': 'lijun'}

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 24}, '': 'LIJUN'}

{'': 'xiaoyu', '': {'name': 'chenlijun', 'age': 24}, '': 'lijun'}

 credit_card = {"name":"至尊宝","acc":{"id":6210222,"balance":900}}

 credit_card2 = credit_card.copy()

 credit_card2["name"] = "紫霞仙子"

 print(credit_card)

 print(credit_card2)

 credit_card["acc"]["balance"] -= 300

 print(credit_card)

 print(credit_card2)

 credit_card2["acc"]["balance"] -= 500

 print(credit_card)

 print(credit_card2)

{'name': '至尊宝', 'acc': {'balance': 900, 'id': 6210222}}

{'name': '紫霞仙子', 'acc': {'balance': 900, 'id': 6210222}}

{'name': '至尊宝', 'acc': {'balance': 600, 'id': 6210222}}

{'name': '紫霞仙子', 'acc': {'balance': 600, 'id': 6210222}}

{'name': '至尊宝', 'acc': {'balance': 100, 'id': 6210222}}

{'name': '紫霞仙子', 'acc': {'balance': 100, 'id': 6210222}}

 f = open("lyrie",mode="a",encoding="utf-8")

 f.write("\nPlease input send str...")

 f.write("\nPlease input send str...")

 f.write("\nPlease input send str...")

 f.close()

 f = open("lyrie",mode="r",encoding="utf-8")

 date = f.read()

 date = date.replace("input","hahahhha")

 f.close()

 f = open("lyrie",mode="w",encoding="utf-8")

 f.write(date)

 f.close()

 import os                       #导入模块

 f = open("lyrie",mode="r",encoding="utf-8")

 f_new = open("lyrie_new",mode="w",encoding="utf-8")

 for line in f:

     print(line)                 #循环一行行读

     if "Please" in line:

         line = line.replace("Please","aaa")

     f_new.write(line)

 f.close()

 f_new.close()

 os.remove("lyrie")

 os.rename("lyrie_new","lyrie")

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","r+",encoding="utf-8")

print(f.read())

f.write("--------test------")

f.close()

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","w+",encoding="utf-8")

print(f.read())

f.write("--------test------")

f.close()

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","r",encoding="utf-8")

print(f.read())

print("--------------------------")

print(f.read())　　　　　　　　　　　　　　

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","r",encoding="utf-8")

print('cursor:',f.tell())

print(f.read())

print('cursor:',f.tell())

print("--------------------------")

print(f.read())

print('cursor:',f.tell())

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","r",encoding="utf-8")

print('cursor:',f.tell())

f.seek(10)                      #代表移动10个字节，不是10个字符。

print('cursor:',f.tell())

print(f.read(5))                #读的时候是字符，5个字符。

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

f = open("lyrie","a+",encoding="utf-8")

f.write("--------哈哈------")

f.seek(0)

print(f.read())

f.close()

f = open("lyrie","rb")

print(f.read())

f.close()

# -*- coding: UTF-8 -*-

#blog:http://www.cnblogs.com/linux-chenyang/

import sys

print(sys.argv)

oldstr = sys.argv[1]

newstr = sys.argv[2]

print(oldstr,newstr)

def close(self): # real signature unknown; restored from __doc__

        """

        Close the file.

        A closed file cannot be used for further I/O operations.  close() may be

        called more than once without error.

        """

        pass

    def fileno(self, *args, **kwargs): # real signature unknown

        """ Return the underlying file descriptor (an integer). """

        pass

    def isatty(self, *args, **kwargs): # real signature unknown

        """ True if the file is connected to a TTY device. """

        pass

    def read(self, size=-1): # known case of _io.FileIO.read

        """

        注意，不一定能全读回来

        Read at most size bytes, returned as bytes.

        Only makes one system call, so less data may be returned than requested.

        In non-blocking mode, returns None if no data is available.

        Return an empty bytes object at EOF.

        """

        return ""

    def readable(self, *args, **kwargs): # real signature unknown

        """ True if file was opened in a read mode. """

        pass

    def readall(self, *args, **kwargs): # real signature unknown

        """

        Read all data from the file, returned as bytes.

        In non-blocking mode, returns as much as is immediately available,

        or None if no data is available.  Return an empty bytes object at EOF.

        """

        pass

    def readinto(self): # real signature unknown; restored from __doc__

        """ Same as RawIOBase.readinto(). """

        pass #不要用,没人知道它是干嘛用的

    def seek(self, *args, **kwargs): # real signature unknown

        """

        Move to new file position and return the file position.

        Argument offset is a byte count.  Optional argument whence defaults to

        SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values

        are SEEK_CUR or 1 (move relative to current position, positive or negative),

        and SEEK_END or 2 (move relative to end of file, usually negative, although

        many platforms allow seeking beyond the end of a file).

        Note that not all file objects are seekable.

        """

        pass

    def seekable(self, *args, **kwargs): # real signature unknown

        """ True if file supports random-access. """

        pass

    def tell(self, *args, **kwargs): # real signature unknown

        """

        Current file position.

        Can raise OSError for non seekable files.

        """

        pass

    def truncate(self, *args, **kwargs): # real signature unknown

        """

        Truncate the file to at most size bytes and return the truncated size.

        Size defaults to the current file position, as returned by tell().

        The current file position is changed to the value of size.

        """

        pass

    def writable(self, *args, **kwargs): # real signature unknown

        """ True if file was opened in a write mode. """

        pass

    def write(self, *args, **kwargs): # real signature unknown

        """

        Write bytes b to file, return number written.

        Only makes one system call, so not all of the data may be written.

        The number of bytes actually written is returned.  In non-blocking mode,

        returns None if the write would block.

        """

        pass

　　 flush() 强制从内存中写入到硬盘，不用close，可以减少硬盘的读取操作。